Theme 1C Flashcards
What is semiconservative replication
Each daughter strand is paired with its complimentary parent strand
Blue red
What is conservative replication
Both daughter strands pair up together and parent strands pair together
Red red blue blue
What is dispersive replication
Daughter strands have a mix of parental and newly made dna
Mix of blue and red throughout whole dna
What is the Meselson and stahl experiment
They put nitrogen isotopes N15, N14 into the DNA molecule through the nitrogenous bases.
They spun the N 15 solution and found that it appeared as a single N15 band.
Then they transferred it to the N14 solution and replicated it, DNA showed a single band intermediate between the N15 and N14 isotope.
They replicated it again in the N14 medium and it showed as two bands, one in the intermediate between N15 and N14, and the other only in the N14 position. This means there were some hybrid daughter/parent strand dna, and some only new daughter dna
Experiment showed that ecoli was semiconservative replication
What direction does DNA replication occur? Why
5’-3’
Nucleotides can only be added to the 3’ OH end of the strand
How is the new dna backbone able to be formed during replication
The hydrolysis of phosphate provides energy for the formation of the phosphodiester bond.
It’s does this by cleaving off two phosphates out of three, and these two phosphates (pyrophosphate) provide energy.
The other phosphate stays in the daughter strand backbone
What direction does the dna polymerase read the parent strand during replication
3-5
What does DNA polymerase need to make a new daughter strand
An RNA primer to kickstart synthesis
What is a replisome
The molecule machine of enzymes that replicates DNA
What is helicase
Unwinds the double helix by braking the hydrogen bonds
What is primase
The enzyme that makes RNA primers for DNA pol to start replicating
What is the single stranded binding protien
The protien that attaches to single stranded DNA before replication
stabilizes (prevents reannealing) so it can act as template
What is DNA topoisomerase/gyrase
The enzyme that relaxes dna and prevents coils/ tangles from forming ahead of the replication fork
Relives torque
What is DNA pol III
Makes the new daughter strand by adding nucleotides to the new DNA strand/rna primer
What is DNA pol I
It remove the RNA primer and fill the gap made by the removal with dna (dNTPs)